Reducing accidental shrew mortality associated with small-mammal livetrapping II: a field experiment with bait supplementation by Randy Do, Julia Shonfield, and Andrew G. McAdam

October 23rd, 2013 | Research

The CAHT funding of the valuable research was made possible through your donations. The paper is published in Volume 94, Issue 4 of the Journal of Mammalogy. The full article is available for a fee through


Accidental mortality is pervasive in small mammal live trapping studies and presents a welfare concern for the particularly vulnerable shrews (Soricomorpha: Soricidae). Although small mammal researchers are aware of this problem and generally suspect that high mortality rates are caused by nutritional constraints and potentially high moisture requirements, these hypotheses have not been widely tested and the problem persists for lack of a practical solution. We conducted a field experiment to assess the effects of providing either high-energy palatable food or water supplements on mortality rates of Blarina brevicauda and Sorex spp. using standard small mammal livetrapping techniques. Water supplements had no effect on shrew mortality, but mortality rates declined by 49% for B. brevicauda and by 64% forSorex spp. when sunflower seed bait was supplemented with 4 g of mealworms (Tenebrio molitor) compared to controls. Furthermore, the addition of mealworms as a bait supplement eliminated the adverse effect on mortality of the length of time that Sorex were in traps prior to release. The supplementation of live-trap baits with mealworms, therefore, represents a practical method for small mammal researchers to reduce accidental shrew mortality during small mammal live trapping.